1. Field of the Invention
The present invention relates to a lens holder capable of confirming a mounted state of a lens and a lens shape measuring apparatus using the lens holder and configured to measure a lens shape such as a lens shape of an eyeglass frame, a shape of a demo lens, a template for a lens, or the like.
2. Description of the Related Art
There is conventionally known a lens holder used for holding a lens, a template, a demo lens or the like when measuring a shape of the lens and so on, or used for holding an eyeglass lens between a pair of lens rotating shafts of a lens contour processing apparatus when grinding the eyeglass lens.
As the lens holder, there exists a flange type lens holder in which a flange, for example, an elongate egg-shaped flange is integrally provided on one end of a shaft portion, or a lens absorbing jig (absorbing cup) in which a rubber cup is integrally provided on one end of a shaft portion.
As this flange-type lens holder, there is known an adhesive-type lens holder in which the lens shape is adhered to the flange by a double-faced adhesive tape, or a screw fixing-type lens shape in which a positioning pin provided on the flange is engaged in a positioning hole of a template and the template is fixed to the flange by means of a fixing screw inserted into a center hole of the template. Meanwhile, in the lens absorbing jig, the lens can be held on the shaft portion by absorbing the lens to a rubber cup.
By the way, there is known a lens shape measuring apparatus in which a shaft portion of a lens holding member configured to hold a lens is fitted in a cylinder or engaging tube portion of a lens holder. The lens holder is set to the lens shape measuring apparatus in such a manner that the lens is located downward, a circumferential edge of the lens is measured by a measuring element from below, and lens shape data (lens shape information) for processing a contour of the eyeglass lens is obtained (for reference, see Japanese Patent No. 3602175, FIG. 10).
In addition, there is conventionally known a lens shape measuring apparatus for an eyeglass lens frame wherein, for example, a lens is attached to a lens absorbing jig. A cylinder or engaging tube portion of a lens holder is clamped to a shaft portion of a lens absorbing jig by means of a circular clamping member provided on the lens holder. The lens is located downward and thus the lens holder is set to the apparatus, a circumferential edge of the lens is measured by a measuring element from below, and lens shape information for processing an eyeglass lens (lens shape information) is obtained (for reference, see Japanese Patent No. 3989593, FIG. 6).
However, in the aforementioned lens shape measuring apparatus, if the shaft portion of the lens holder by which the lens is held is engaged in the cylinder or engaging tube portion without providing a clamping member in the lens holder, since the engaging tube portion of the lens holder is directed downward, in the case that an engaging state of the shaft portion to the engaging tube portion is loose, when measuring the lens shape contour by abutting the measuring element against the circumference edge of the lens, the lens holding member and the lens are out of place from the engaging tube portion of the lens holder, there is a problem that the lens shape contour cannot be correctly measured.
Further, a lens can be shaped like an elongate crab eye having a short height (crab eye-like lens shape) such as a recent rimless frame in which holes for mounting metal fittings are formed. In the case that a lens shape as mentioned above is measured by the lens shape measuring apparatus, if the lens like the elongate crab eye (crab eye-like lens shape) is attached to a normal lens holding member, the positions of the holes are hidden, so that there is a possibility that the positions of the holes cannot be correctly detected.
Accordingly, if the positions of the holes cannot be correctly detected, since there are no data concerning the positions of the holes of the lens, the circumferential edge of the eyeglass is processed by the lens processing apparatus based upon the above-mentioned lens shape information. After the finishing process of the thus ground eyeglass, when forming the holes in the eyeglass, there has been a possibility that the holes are formed in wrong positions.
Furthermore, in the above-mentioned lens shape measuring apparatus, since the clamping member of the lens is circular in shape, such as a recent rimless frame, if the lens like the elongate crab eye having a short height (crab eye-like lens shape) is attached to the lens of a normal lens holding member, the positions of the holes cannot be detected. Since the positions of the holes cannot be correctly recognized, after the finishing process of the thus ground eyeglass, when forming holes in the eyeglass, there has been a possibility that the holes would be formed in wrong positions.